North of Lies lies the Koegelwieck, the largest secondary dune valley of Terschelling, created during a large shifting period on the island in the 19th century. It has an enormous wealth of plants and is therefore a protected nature reserve. There are several hiking trails through the vulnerable area, so you can fully enjoy this beautiful part of Terschelling. In winter, a lot of dune water remains here, so that the paths are no longer accessible. Sometimes even whole pieces of adjacent forest are under water, where even the islanders participating in 'the Terschelling survival' can be mistaken! Due to the breeding season, it is not allowed to leave the roads and paths from March 15 to July 15.